Facial bones:Maxilla
The maxillae bones are one of the facial bones, forming the upper jaw and palate of the mouth. The two halves are fused at the intermaxillary suture to form the upper jaw. Each maxillae consists of: * The body of the maxilla * Four processes ** The zygomatic process ** The frontal process of maxilla (orbital and lateral wall of nasal cavity) ** The alveolar process: holds the upper teeth, and is referred to as the maxillary arch. ** The palatine process (floor of nasal cavity) * Infraorbital foramen * The maxillary sinus: a pyramid-shaped paranasal sinus which drains into the middle meatus of the nose. It is the largest of the paranasal sinuses. Articulations: each maxilla articulates with nine bones: * two of the cranium: the frontal and ethmoid * seven of the face: the nasal, zygomatic, lacrimal, inferior nasal concha, palatine, vomer, and the adjacent fused maxilla. Development: The maxilla is ossified from two centers only, one for the maxilla proper and one for the premaxilla. These centers appear during the sixth week of fetal life and unite in the beginning of the third month, but the suture between the two portions persists on the palate until nearly middle life. Mall states that the frontal process is developed from both centers. Each maxilla also enters into the formation of two fossae: the infratemporal and pterygopalatine, and two fissures, the inferior orbital and pterygomaxillary. Maxillary sinus The space with the body of the maxilla. This sinus is pyramidal in shape with the apex in the zygomatic process of the maxilla and base at the lateral wall of the nose. - roof: floor of the orbit. A ridge projects downwards, houses the passage of the intraorbital nerve within its canal. - floor: the alveolar process of the maxilla - posterior wall - infratemporal and pterygopalatine fossae - anterior wall: cheek It is present at birth but as a slit on the medial side of the floor of the orbit, and it begin to develop until around the age of 14 years. The body of the neonatal maxilla lateral to this is full of developing teeth. The sinus increase in size, and after the second dentition, the floor of the sinus is level with the floor of the nose. Rapid growth of the sinus occurs after puberty. Drainage: ostium of the sinus is superior and posterior on its medial wall. Its 2-4mm, and opens at the posteriior part of the infundibulum in the middle meatus of the lateral wall of the nose. An accessory ostium may open anterior to posterior to the lower part of the uncinate process Blood supply: - arterial: small arteries from the facial, maxillary, infraoribtal and greater palatine - venous: accompany arteries to the facial vein and pterygoid plexus Lymph drainage: - submandibular nodes Nerve supply: - infraorbital and superior alveolar branches of the maxillary nerve. The alveolar nerves run down to the teeth in the walls of the sinus, and these minute branches pierce the bone to supply the mucous membrane of the sinus.